I am trying to prepare a package for students that offers a uniform standard title page for their work (homework, reports, theses, and probably more).
I have the title page laid out as it should be. However, I am having problems setting the margins. I wish to centre ONLY the title page, without side effects to possible margin settings that the students might have already set up for the rest of their document.
I have seen other solutions such as this one, but they invariably make use of some package like geometry etc. I am seeking a solution that works with plain LaTeX only. The reason is that I do not know what class the title page package ends up in (book, report, memoir, classicthesis, ...), and I need something that provides maximum compatibility.

pdfpagespackage to include it. Nothing you do is going to be compatible inline with absolutely anything they might be using. – cfr Sep 07 '15 at 21:26pdfpagessolution, as this is what I do for my own thesis title page. But for someone maybe new to TeX, and more importantly maybe already struggling to get the required work done, a two-step process is far worse than accepting small incompatibilities with e.g. thegeometrypackage. And sincegeometrydoes it, it should be doable, right? – Sep 07 '15 at 21:34plain LaTeXexactly? Note that classes and packages do not just add things, they change things. So, by\begin{document},\macroAmay not do the same thing in student 1's document as it does in student 2's. I'm no guru but everything I know suggests that you simply can't do this in a way which will be compatible with every student's work: not if they could be using literally any combination of class and packages. Not using a package doesn't mean compatible with everything. Packages are just code. Code changes stuff. – cfr Sep 07 '15 at 21:51\newgeometry,\restoregeometry, ... commands fromgeometrydo. – Sep 07 '15 at 22:08